The author outlines a classroom tariff-setting game that allows students to explore the consequences of import tariffs imposed by large countries (countries able to influence world prices). Groups of students represent countries, which are organized into trading pairs. Each group's objective is to maximize welfare by choosing an appropriate ad valorem tariff that may be changed intermittently throughout the game. The game is built on a computable general-equilibrium model, which allows each nation's utility and terms of trade under alternative tariff regimes to be expressed quantitatively. The exercise encourages students to consider terms-of-trade improvements and efficiency losses resulting from large-country tariffs and provides a framework to discuss the Nash equilibrium of a tariff war. The game is a useful supplement to traditional teaching methods. (Contains 2 tables, 2 figures and 11 notes.)